Which out of the 4 RAM slots are used for dual channel performance on this laptop? Zbook 15 G3

[bizbarley]

I wanted to know what slots I should put RAM chips in, out of the four available for dual channel performance? Which number on the ports should I use if I was going to add 2x16gbs of RAM?

[BeemerBiker]

According to the spec for your Zbook 15 G3 there are only two slots for memory.

https://support.hp.com/us-en/document/c04920622#AbT5

The service manual only states that if a single memory is to be used it has to go into slot "1"

see page 44

http://www1.hp.com/ctg/Manual/c04887250.pdf

[TzortzisG]

Hi!

@BeemerBikerYou're looking at an inferior model to the one bizbarley has.

Hello bizbarley.

Your ZBook's specifications sheet can be seen here, and it indeed has 4 RAM slots.

The answer to your question is in the ZBook G3 manual, pages36-37.

Take care!

[bizbarley]

Yes thank you for pointing out the misunderstanding in models.

I reviewed the manual before posting, specifically those pages. However, and I do have something of a learning disability so please bare with me, although it numbers the slots 1-4, it was not clear to my satisfaction which chip ports I should use for dual channel performance. 

In the manual picture you provided, is it correct that chip sockets labeled 1&2 would give me dual channel memory? Can you confirm that for me please? If this is the case I will mark this as solved. I've asked this question and searched for an answer the last couple of days and no one seemed to be familiar with any laptops that included 4 so-dimm slots. People told me I was confused.

Thank you kindly for your understanding and your patience. It means a lot to me.

[BeemerBiker]

Slots numbered 1 and 2 should be filled with matching memory.  If you have another pair they would go into slots 3 and 4.

You can use the app CPU-z to determine if the memory is running in dual channel mode.  Download it here.

Alternately, you bios may have information such as

Page 36 describes the method of removing memory.  Those precautions (5 steps) also apply to inserting memory.

I suggest to test the system's new memory before fully re-assembling the case.  You might consider having a professional do this as they will have the tools and anti-static materials.

[TzortzisG]

Yes, I also confirm BeemerBiker's interpretation of the manual. The numbers 1 and 2 (and then 3 and 4) are the slots that have priority when you install the RAM modules, so as to get the best performance. For slots 1 and 2, this means dual-channel performance.

This old Notebookcheck review of your model shows how HP factory-fitted the two 16GB RAM modules, and they are in slots 1 and 2.

There is also this old post (https://h30434.www3.hp.com/t5/Notebooks-Archive-Read-Only/ZBook-17-G3-Mix-memory-modules-of-differen...) by @Huffer EXPERT Level 18 where he explains that RAM modules in slots 1 and 3 work in dual-channel mode, so it's quite possible installing either way will lead to a correctly working config.

bizbarley, you can mark BeemerBiker's reply above as solution if you want. @BeemerBiker 👍

[bizbarley · Accepted solution]

Excellent. Thank you guys so much for the quick and detailed responses. I ended up ordering another 2 chips of 2x8gbs (16gbs) of RAM that was on sale. So now I have 4x8gbs (32gbs) with all slots filled. Personally I would have gone with 2x16gbs (32gbs) for dual channel, but it was a bit more than I wanted to spend. Also it would have meant tossing the 2x8gb sticks the laptop came with. After installing the new RAM, on my next post I got an error message, but it was just saying the the laptop found a different memory configuration, and to press enter to properly configure the new setup. I did that, the error message disappeared, the laptop now shows 32gbs, CPU-Z (excellent recommendation btw) shows dual channel, so does MSI Afterburner, and the task manager also confirms 4 of 4 sodimm slots filled and functioning correctly at maximum clock speed (2133mhz). 

Thanks again experts,  your help means a lot to me. Issue solved. Cheers!